In mounting expensive artwork in frames, it is the normal procedure to mount a glass or plastic sheet or panel in front of the artwork to protect it against dust and moisture and other possibly damaging effects. It is also important to keep front sheet adequately spaced from the artwork so that there will be no engagement between the two which would cause structural damage to the artwork such as ink transfer, mold growth (foxing) and buckling. Preferably dust and dirt particles should be kept out of the space between the sheet and the artwork so that the artwork is effectively preserved for long periods of time and does not become discolored or otherwise affected by foreign particles in the space.
Attempts have been made in the past to use spacers to space the sheet from the artwork. Balsa wood, plastic and cardboard spacers have been used for this purpose. Such spacers have to be glued to the adjacent frame member. This technique is not satisfactory because the glue often becomes loose, the spacers buckle, and the artwork is not properly spaced from the glass or plastic front sheet when this occurs. Also, the materials now used as spacers may themselves cause damage to the artwork because of acid content or, if painted, paint transfer to the artwork.
Other attempts have included the use of a transversely C-shaped spacer which has been too small in thickness to space the artwork any more than 1/16 inch away from the sheet. This spacer presents too small a space between the front sheet and the artwork because 1/16 inch is an inadequate space for many embossed, thick or naturally wavy pieces of art.
The mounting of panels in frame members, such as window panes or the like, have been known in the past. Typical disclosures of concepts of this type are set forth in U.S. Pat. Nos. 2,126,167, 2,189,137 and 2,308,918.
Because of the limitations of spacer units for frames for artwork which have been heretofore used, a need has arisen for an improved spacer or fillet which effectively spaces the transparent sheet in the front of the artwork from the artwork itself while permitting easy assembly of the artwork and sheet into a frame without special skills and tools.